package LinkedList;

public class MergeTwoLists {
    public static void main(String[] args) {

    }

    public ListNode mergeTwoLists(ListNode list1, ListNode list2){
        // 判断特殊情况：空链表等
        if(list1 == null && list2 == null){
            return null;
        }
        if (list1 == null) return list2;
        if (list2 == null) return list1;

        ListNode dummy = new ListNode(0);
        ListNode cur = dummy;
        while (list1 != null && list2 != null) {
            if (list1.val < list2.val) {
                cur.next = list1;
                list1 = list1.next;
            }
            else {
                cur.next = list2;
                list2 = list2.next;
            }
            cur = cur.next;
        }
        cur.next = list1 != null ? list1 : list2;
        return dummy.next;
    }
}
